1. Field of the Invention
This invention pertains to interpolation of seismic data from a plurality of recorded seismic traces and more specifically by performing a dip range analysis on a plurality of seismic traces and by examining the trace envelope of the seismic traces.
2. Description of the Prior Art
In interpreting or processing data recorded in seismic traces it is desirable that the traces be evenly spaced and sufficiently close together. The practice of seismic surveying techniques nevertheless encounters various obstacles that prevent this and thereby necessitate interpolation of the missing data. Another problem often arises in that the cost of the seismic survey is directly dependent on the number of traces collected and so the receivers are frequently spaced further apart than is desirable. Intermediate traces must then be interpolated from those that are recorded.
Interpolation methods in the prior art generally attempt to estimate a new trace by connecting the troughs and peaks representing reflected arrivals in recorded traces along a dip, a dip being defined as the rate of change in the time of arrival per trace. These methods typically examine the recorded traces along a number of preselected experimental dips in order to determine the correct dip of the reflected arrivals and thereafter interpolate a reflected arrival in the new trace along the correct dip. Alternately, interpolated traces may be generated by inserting zero traces at the interpolation locations and following with an appropriate spatial filter. This alternate approach requires that the signal dips be approximately known a priori.
The prior art breaks down or is insufficient in the presence of aliasing in the recorded traces. Aliasing is defined as the condition wherein a dip is sufficiently large so that there is difficulty in correlating the peaks and troughs in successive recorded traces, typically when successive traces are greater than or equal to one-half cycle out of phase. The prior art also fails when the recorded traces exhibit a plurality of dips because of an inability to adequately separate the reflected arrivals.
It is therefore a feature of the present method to provide an improved method for the interpolation of seismic traces that will accurately interpolate seismic data in the presence or absence of aliasing.
It is a further feature of the method herein disclosed that it will interpolate from a plurality of dips in the recorded traces.
It is still a further feature that the method will interpolate properly when the signal dips are not known a priori.